Today, in addition to the display, the keyboard and the other peripheral devices, a so-called mouse is usually connected with a thin cord or cordlessly to the central processing unit. When moved about, the mouse enables easier control of the cursor on the display and serves to replace the cursor control buttons on the keyboard. The mouse is a pointing device which usually comprises a small box that is moved about on a desktop, the box having on its underside a ball that communicates information on the movement of the mouse to the computer's central processing unit. Between the mouse and the operating system there is a program, the mouse driver, which in conjunction with the operating system then converts the movement of the mouse ball to a corresponding scaled cursor movement on the display. The use of a mouse is today in practice a necessity in various graphical user interfaces such as GEM (Graphics Environment Master) and Microsoft Windows. In these programs the mouse is used to move the cursor and to point and mark areas.
In present-day solutions the movement of the mouse ball is converted directly to scaled movement in the corresponding direction on the display. In general, scaling is such that moving the cursor, for example, from one edge of the display to the other requires that the mouse make a very long sweep on the desktop or that the mouse be lifted from the desktop, the same movement being repeated several times. The length of the sweeps grows as displays become larger and the resolution of display controllers increases. It has previously been attempted to correct the problem by reducing the range of movement before a long sweep by changing the resolution of the pointing device (scaling). The change in resolution nevertheless makes use of the pointing device slower.